don't use 'cc -f' with compilers that don't do automatic double to

[unix-history] / usr / src / usr.bin / f77 / libF77 / z_sqrt.c

/*
* Copyright (c) 1980 Regents of the University of California.
* All rights reserved.  The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*
*      @(#)z_sqrt.c    5.2     %G%
*/

#include "complex"
#ifdef tahoe
#include <tahoemath/FP.h>
#define cabs zabs
#endif tahoe

z_sqrt(r, z)
dcomplex *r, *z;
{
double mag, sqrt(), cabs();

if( (mag = cabs(z->dreal, z->dimag)) == 0.)
       r->dreal = r->dimag = 0.;
else if(z->dreal > 0)
       {
       r->dreal = sqrt(0.5 * (mag + z->dreal) );
       r->dimag = z->dimag / r->dreal / 2;
       }
else
       {
       r->dimag = sqrt(0.5 * (mag - z->dreal) );
       if(z->dimag < 0)
#ifndef tahoe
               r->dimag = - r->dimag;
#else tahoe
               *((long int *)&r->dimag) ^= SIGN_BIT;
#endif tahoe
       r->dreal = z->dimag / r->dimag / 2;
       }
}